1. Field of the Invention
The present invention relates to a forced air cooler for a belt type transmission contained in a power unit of vehicles such as motorcycles.
2. Description of the Prior Art
A cooler is known for forcibly air-cooling a belt type transmission in a transmission casing by forcibly introducing the open air into the transmission casing in a power unit for vehicles. The transmission casing is provided at one side of an engine body and the belt type transmission composed of a drive pulley connected with the engine body, a driven pulley connected with an output shaft and an endless transmitting belt engaged between the pulleys is contained in the transmission chamber of the transmission casing. This device is disclosed and known in Japanese Utility Model Publication Laid-open No. 101047/1983, for example.
However, in such conventionally known coolers for a belt type transmission operated in a transmission casing, the flow of cooling air introduced into the transmission casing typically interferes with an air stream generated by the operation of the belt type transmission such that the air flows partially collide with each other. This generates stagnation in the air to lower the cooling efficiency. Particularly when the belt type transmission is operated at high speeds, this trend disadvantageously increases.
In addition, in such coolers, a direct air intake passage is formed in the front portion of the transmission casing. Thus, there is limited space to increase the area of the passage. In this case, the flow rate of the air drawn into the transmission casing tends to become insufficient, thereby causing the cooling efficiency to decrease. Further, the structure of the entire cooler is complicated to disadvantageously increases its cost.